At 05:22 PM 11/6/2007, you wrote:
Hi David,
Thanks for your reply. This helped greatly.
Yeah, I supposed I could just randomly flip bits in the MySQL files
and that would do the trick.
The program I'm writing does first attempt to repair the tables with
MySQL's utilities if they're MyISAM but InnoDB tables don't support
repair and this program is actually meant to be a potential stop-gap
solution in the event of hardware errors in a non-failover situation
which can do really horrible things like corrupt InnoDB inodes thus
rendering tables unusable to keep clients seeing SOMETHING (even if
it's stale data) until the hardware can be swapped out.
Speaking of which, can anyone think of a reason that InnoDB tables
would corrupt aside from hardware problems or a bug in the storage
engine?
David,
Bad network cards could corrupt the data or flaky memory.
Here are a few links that deal with InnoDb corruption.
http://www.mysqlperformanceblog.com/2006/07/30/mysql-crash-recovery/
http://www.mysqlperformanceblog.com/2007/05/22/magic-innodb-recovery-self-healing/
http://www.google.ca/search?hl=en&q=innodb+corruption+causes&btnG=Search&meta=
Mike
On Nov 6, 2007 6:04 PM, David T. Ashley <[EMAIL PROTECTED]> wrote:
> On 11/6/07, mos <[EMAIL PROTECTED]> wrote:
> >
> > At 02:18 PM 11/6/2007, Richard Edward Horner wrote:
> > >Hi,
> > >
> > >I'm working on a program that will run in the event that tables are
> > >crashed or corrupt. Can anyone recommend a good method for crashing my
> > >tables or corrupting them so I have some test cases? I'm mostly
> > >interested in MyISAM and InnoDB table types.
> > >
> > >I was thinking I would just start an infinite loop with an UPDATE
> > >statement in it and then kill -9 the mysqld process.
> > >
> > >Any better ideas?
>
>
> Well, there are different types of corruption. Here are a few that come to
> mind:
>
> a)Corruption of a MySQL file, perhaps not repairable (disk hardware
problem,
> OS crash, server power supply failure).
>
> b)Corruption in a way that is repairable by a MySQL utility (index file
> corrupted).
>
> c)Application corruption (bad application doesn't handle mutual exclusion
> correctly, has logical errors, etc.).
>
> Hopefully database repair utilities that come with MySQL will map (a) and
> (b) to be indistinguishable from (c). (But I don't know that--I'm barely a
> MySQL user.)
>
> The most even-handed way to do it would seem to be:
>
> a)Write a program that will create a random number of distributed and block
> corruptions distributed randomly in the MySQL files. (Such a program would
> take very little time to execute--well under half a second, I'm guessing.)
> You might want to throw in truncations and blocks added at the end of
files,
> too.
>
> b)See how far the MySQL utilities (if there are any) followed by your
> software will go towards repair.
>
> Doesn't seem like an easy thing to test.
>
--
Richard Edward Horner
Engineer / Composer / Electric Guitar Virtuoso
[EMAIL PROTECTED]
http://richhorner.com - updated June 28th
--
MySQL General Mailing List
For list archives: http://lists.mysql.com/mysql
To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
--
MySQL General Mailing List
For list archives: http://lists.mysql.com/mysql
To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
